Below Cave Point

Below Cave Point11 bedrock mortars all one one rock.

Think those big holes are geoconcretions? Think again. They are huge bowl mortars. Their side walls bulge out into the surrounding rock in a classic “Olla” shape–the bowl is wider at the side walls than it is at the rim. The bottoms of these bowls are basically flat, not rounded, and they all have small mortars at their centers.

These two bowls resemble volvanic caldera. Note the flattened and worn areas surrounding the mortar mouths. When you visit this site, stand on them. It’s hard to resist the impression that someone once stood in the same place stirring hot rocks through water, acorn mush, or some other viscous foodstuff. If you visit in the summer or fall, look carefully at the side walls of the largest bowl. It’s a tough call for us amateurs to make, but the striations there sure look like they could have been produced by moving rocks.

A closeup of the largest bowl. It’s hard to appreciate the “Olla” in this light, but the central mortar and the bowl’s flat bottom stand out clearly. The gray, worn, flat surface on the right side of the bowl even looks like a footpad.